Generic fields Modules (field_modules) - Modules referenced by article/tip/resource. Related modules (field_related_modules) - Used for suggesting related modules, not directly used by article/tip/resource. Used as see also on modules.
Content specific fields Change record module (field_change_record_module) - Module referenced by change record. Issue module (field_issue_module) - Module the issue is for.
Module fields Module issues (field_module_issues) - Issues for module, used in CER.